Hypertrophic obstructive cardiomyopathy (HOCM) is characterized by a dynamic left ventricular outlet tract (LVOT) obstruction, which may be exacerbated by reduced preload and Valsalva. Laparoscopic adjustable gastric band (LAGB) placement is a restrictive bariatric procedure which may be complicated by recurrent vomiting and Valsalva. Pre-operative cardiac evaluation of patients scheduled for LAGB usually focuses on ischemic heart disease. Reported here is the case of a 64-year-old female admitted for evaluation of recurrent pre-syncopal episodes. The patient was diagnosed with HOCM with a significant increase in an LVOT pressure gradient during Valsalva. Thus, recurrent vomiting secondary to LAGB exacerbated a pre-existing cardiomyopathy. Symptoms resolved after gastric band deflation. This is the first report of such a complication after LAGB, demonstrating the hemodynamics of HOCM in a unique setting and underscoring the need for a structural cardiac assessment prior to bariatric surgery.